A bus is a shared communication medium that can be used by different bus station circuits to transmit messages to each other. The messages are sent from source station circuits to destination station circuits and each message typically carries a destination address to identify the destination station circuit. One problem in such a system is that the start of messages has to be indicated in order to locate the destination address and/or command data in the message.
Various techniques are known for indicating the start of messages. US patent application No. 2003/0225951 describes the use of a special signal line to issue synchronization signals, who's timing indicates the start of messages. Another solution is to transmit a predetermined unique sync pattern on the same line (or lines) as the messages. Typically such a predetermined sync pattern is transmitted at the start of each message, to alert the stations to the start of the message.
However, these synchronization techniques involve overhead that increases the complexity of the system and/or decreases the number of messages that can be sent in a given time interval.